Add guard pages in front of platform allocations

src/platform-macos.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 162 matching lines @@
 
 void OS::Protect(void* address, size_t size) {
   UNIMPLEMENTED();
 }
 
 
 void OS::Unprotect(void* address, size_t size, bool is_executable) {
   UNIMPLEMENTED();
 }
 
-#endif
+void OS::Guard(void* address, const size_t size) {
+  mprotect(address, size, PROT_NONE);
+}
+
+#endif  // ENABLE_HEAP_PROTECTION
 
 
 void OS::Sleep(int milliseconds) {
   usleep(1000 * milliseconds);
 }
 
 
 void OS::Abort() {
   // Redirect to std abort to signal abnormal program termination
   abort();
@@ skipping 623 matching lines @@
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal